1. Field of the Invention
The present invention relates to a new system and method for removing soil gas from in a safe and effective manner from the ground surrounding a building structure.
2. Background Art
Radon is an invisible, odorless, tasteless radioactive gas produced by the natural decay of uranium in the soil. The Center for Disease Control in Atlanta, Georgia has reported that human exposure to radon gas is the primary cause of lung cancer, except for cigarettes. Such human exposure routinely occurs from radon gas that seeps from the ground into dwellings and other building structures. Scientists estimate that 20,000 Americans die annually as a result of radon exposure.
In a recent study completed by the Environmental Protection Agency (1988) in a seven state area, it was found that one home in three had dangerous levels of radon gas. The EPA has set a recommended level for remedial action at 4 picocuries per liter, which is equivalent to 200 chest x-rays per year. Even at this level studies have indicated that almost 5 people out of 100 exposed to high levels of radon will die of radon-induced lung cancer.
Conventional dwellings and other building structures are typically built upon foundation walls which define the basement area. The foundation walls and the footers are in direct contact with the ground surrounding the building structure. Most such building structures have an existing drain tile system in the immediate proximity of the foundation, which enables water and debris immediately surrounding the building structure to drain away therefrom. The drain tile system is generally located within a bed of water-permable material such as gravel, the gravel bed surrounding the building structure.
The drain tile system is generally located around the perimeter of the building structure slightly below the foundation, either directly under the perimeter of the building structure or surrounding the perimeter of the building structure. The drain tile system is made of a water porous tile and is laid in a continuous channel, so that water and contaminants disposed in the vicinity of the building structure can be routed across and through the drain tile system and into a sewer or a sump pump. The drain tile system is generally in fluid communication with a series of interconnecting pipes disposed underneath the building structure. Generally, these interconnecting pipes have gradual bends in the direction of fluid flow and are accessible through several floor drains located in the basement floor of the building structure. The drain tile system feeds into either a sump pump or a centralized sewer.
Soil ventilation draws soil gas away from the building structure. The suction of soil gas through the drain tile system is enhanced by a fan which suctions the soil gas from the soil around the foundation and through the drain tile system and away from the building structure, effectively preventing the soil gas from entering the building structure. Drain tile suction is an inexpensive and nonobtrusive method of active soil ventilation, and such systems have demonstrated reductions in radon gas as high as 99%.
For drain tile suction to be effective, it is critical that the drain tile system must be maintained free from objects which tend to block the normal flow of water therethrough and prevent ventilation of the drain tile system.
Oftentimes, the drain tile system is interconnected to the eaves wherein leaves and twigs, roof tar, and even the remains of small animals may become lodged therein. Since the flow of water and debris through the drain tile is at most a trickle, the drain tile is never flushed. When the drain tile becomes blocked at various locations with debris, as frequently occurs, the drain tile system is extremely difficult to clean. The property owner is confronted with choosing between:
(a) digging several feet deep into all the land surrounding the building structure to access the existing drain tile system, and to locate and remove the blockages; or PA1 (b) inserting a second drain tile system underneath the building structure, and thereby jackhammering major portions of the existing basement floor.
What is needed is a new method and apparatus for cleaning the existing drain tile that overcomes the disadvantages already noted; a method and system which combines the continuous soil ventilation through the drain tile system to remove soil gas from the vicinity of a building structure with a new method and system for keeping the drain tile system free from blockages.